In recent years, use of a digital camera has begun to extend explosively due to improved image quality and decreased price coupled with an improved performance of a personal computer and a color printer. With this as a background, with intention of further extending ownership of the digital camera, various companies have proposed various standards for a method of storing related information such as image pickup conditions of the digital camera and a method of improving an interface with the color printer. On the other hand, a home-use projector is coming to be widely used due to reduced size, weight and price of the body thereof. In the near future, an image picked up by the digital camera is expected to be enjoyed by use of a projector even in ordinary home.
FIG. 1 shows a flowchart for a conventional method of displaying a thumbnail image in an image reproduction device meeting reproduction specifications of a conventional automatic reproduction file.
First, a user inserts an image file storage medium containing an image picked up by a digital camera, into an image reproduction device. An image file storage medium has stored therein a plurality of image files and an automatic reproduction file for automatically setting the image files in an automatic reproduction mode. FIG. 2 shows an example of a file configuration of the image file storage medium. FIG. 2 shows an image file configuration based on DPOF specifications disclosed by four companies including Matsushita Electric Industrial Co., Ltd. The file configuration in the image file storage medium is such that a DCIM folder for storing an ordinary image file and a MISC folder for storing the control information such as automatic reproduction file information are arranged under a ROOT directory. The ordinary image files including ABC0001.JPG, ABC0002.JPG and the like are all placed in the lowest layer of the DCIM folder. An AUTPRTINT.MRK file in the MISC folder is an automatic print file, a UNICODE.MRK file is a unicode character string description file, and an AUTXFER.MRK is an automatic transmission control file. Also, an AUTPLAYn.MRK file is an automatic reproduction file. This automatic reproduction file has stored therein the control information for controlling automatic reproduction of these image files. This control information concerns designation and order of the image file and interval of image transmission time for automatic reproduction. For example, in a case where 10 image files including ABC0001.JPG to ABC0010.JPG are arranged in the lowest layer of the DCIM folder, and three images of ABC0002.JPG, ABC0005.JPG and ABC0009.JPG are designated as automatic reproduction files, the image reproduction device automatically displays only the three image files in that order on a display unit, but does not display the other seven image files.
The image display device can display a list of a plurality of thumbnail images composed of 160×120 pixels. FIG. 3 shows an example configuration of the image file. Generally, the image file picked up by the digital camera and compressed by JPEG scheme is formed of an application marker block, the number of pixels, quantization table and the like (JPEG header) and a compressed data area of a main image. The application marker block has stored therein image-related information such as image pickup conditions and a thumbnail, i.e., the JPEG code with 160×120 pixels compressed, and the JPEG-compressed data of the thumbnail as well as the number of pixels and the quantization table are also held in the thumbnail region. Characters SOI designates a start marker and EOI an end marker.
Now, in FIG. 1, the image file storage medium is inserted into the image reproduction device and a reproduction process is started. First, the presence or absence of the automatic reproduction file is detected. In the presence of the automatic reproduction file, the file is read (step S1). It is then checked whether a thumbnail display is requested or not (step S2), and in the absence of the request, the image file is sequentially automatically reproduced in line with contents described in the automatic reproduction file (steps S3, S4). In a case where the thumbnail display request is input by interruption from an external arbitrary input unit, the process proceeds from step S2 to step S5. The image reproduction device retrieves thumbnail image data of all the image files in the lowest layer of the DCIM folder from the image file storage medium, and displays a thumbnail image list on a display (step S6).
In a case where the operation described above is performed, however, all the thumbnail images are displayed as a list regardless of the information in the automatic reproduction file. Assuming that a large-sized display device such as a projector or a PDP on which a plurality of viewers can view one screen at the same time is used as a display of the image reproduction device, it becomes no problem at the time of normal automatic reproduction because image data not desirably displayed to the viewers are not displayed by internal setting of the automatic reproduction file. In a case where thumbnail display is carried out with intention of searching the image files in the image file storage medium, however, it becomes a problem that the image data not desirably viewed by the viewers are also displayed.